The bbc link is good as you can also get to the mechanics, science and electronics for extra brain use. The maths made easy was useful just for easy explanations to remind my old brain how to do long division and multiplication etc.. There are work sheets on there too so you can keep doing them every day and see your calculation speed increase.
Also..(phew) I use a DS and brain training which has been great for improving my speed of thought.
Also see this linkhttp://www.navy-net.co.uk/Forums/viewtopic/p=408682.html#408682

Yeah had RT in october, just finished everything on the 18th of this month! Not had any joining dates yet, doubt ill get them soon. I've to go back and see my CA in 6months time for catch up interview, and he said he was hopeful that he would RNAC dates for me, then my raleigh dates wouldn't be too long after that